将调整大小的图像上载到S3

Question

我正在尝试将调整大小的图像上载到S3：

fp = urllib.urlopen('http:/example.com/test.png')
img = cStringIO.StringIO(fp.read())

im = Image.open(img)
im2 = im.resize((500, 100), Image.NEAREST)  
AK = 'xx' # Access Key ID 
SK = 'xx' # Secret Access Key

conn = S3Connection(AK,SK) 
b = conn.get_bucket('example')
k = Key(b)
k.key = 'example.png'
k.set_contents_from_filename(im2)

但我有个错误：

 in set_contents_from_filename
    fp = open(filename, 'rb')
TypeError: coercing to Unicode: need string or buffer, instance found

Answer 1

我的猜测是Key.set_contents_from_filename需要一个字符串参数，但您传入的是im2，这是Image.resize返回的其他对象类型。我认为您需要将已调整大小的图像作为名称文件写入文件系统，然后将该文件名传递给k.set_contents_from_filename。否则，在Key类中找到另一个方法，该方法可以从内存构造（StringIO或某个对象实例）中获取图像内容。

Answer 2

print ("loading object", input_bucket, input_key)
response = s3client.get_object(Bucket=input_bucket, Key=input_key)
print("s3 get object response", response)

body = response['Body']

image = Image.open(body)

print ("generating thumbnail", output_width, output_height)

thumbnail = resizeimage.resize_thumbnail(
    image, [output_width, output_height])
body.close()

print ("saving thumbnail", output_format)

with io.BytesIO() as output:
    thumbnail.save(output, output_format)

    print ("uploading thumbnail", output_bucket, output_key)
    output.seek(0)
    s3client.put_object(Bucket=output_bucket, Key=output_key,
                        Body=output, ContentType=output_content_type)

Answer 3

您需要将输出图像转换为一组字节，然后才能上载到s3。您可以将图像写入文件，然后上载文件，也可以使用cStringIO对象避免写入磁盘，正如我在这里所做的：

import boto
import cStringIO
import urllib
import Image

#Retrieve our source image from a URL
fp = urllib.urlopen('http://example.com/test.png')

#Load the URL data into an image
img = cStringIO.StringIO(fp.read())
im = Image.open(img)

#Resize the image
im2 = im.resize((500, 100), Image.NEAREST)  

#NOTE, we're saving the image into a cStringIO object to avoid writing to disk
out_im2 = cStringIO.StringIO()
#You MUST specify the file type because there is no file name to discern it from
im2.save(out_im2, 'PNG')

#Now we connect to our s3 bucket and upload from memory
#credentials stored in environment AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
conn = boto.connect_s3()

#Connect to bucket and create key
b = conn.get_bucket('example')
k = b.new_key('example.png')

#Note we're setting contents from the in-memory string provided by cStringIO
k.set_contents_from_string(out_im2.getvalue())